Fig. 4.

Immunohistochemical (IHC) analysis of D1R expression with age in the lumbar spinal cord. A: dorsal horn. Top left: representative low-resolution micrograph of D1R expression in the dorsal horn of a 2-mo-old animal and its negative control. Bottom left: high-resolution micrograph of the area outlined in the low-resolution picture. Top right: representative low-resolution micrograph of D1R expression in the dorsal horn of a 2-yr-old animal and its negative control. Bottom right: high-resolution micrograph of the area outlined in the low-resolution picture. B: ventral horn. Top left: representative low-resolution micrograph of D1R expression in the ventral horn of a 2-mo-old animal and its negative control. Bottom left: high-resolution micrograph of the area outlined in the low-resolution picture. Top right: representative low-resolution micrograph of D1R expression in the ventral horn of a 2-yr-old animal and its negative control. Bottom right: high-resolution micrograph of the area outlined in the low-resolution picture. D1R labeling is ubiquitous and can be detected throughout the ventral horn (arrowheads). Scale bars, 20 μm.